Joint for concrete slabs



Jan. 9, 1940. E ||l GEYER ET AL 2,186,104

JOINT FOR CONCRETE SLABS Filed Marh 3, 1937 Patented Jan. 9, 1940 PATENTOFFICE 2,186,104, ioINT FOR CONCRETE sLABs Ernest H. Geyer and Henry A.Taubensee, Chicago, I ll.

AApplication March 3, 1937, Serial N0. 128,703

10 Claims.

Toe present invention relates generally to joints for concrete. Moreparticularly the invention relates to that type of joint which isadapted for use between a pair of adjoining or contiguous slabs in aroadway lor like concrete construction, operates as a load transferlunit and at the same time permits of expansion and contraction of theslabs, and comprises (l) an elastic ller strip which is adapted to tbetween the slabs and serves to prevent dirt, water and like matter frompassing between the slabs; (2) aplurality of one-piece cross-sleeveswhich extend between and at right angles to the load distributingbarsand through the meeting faces of the slabs, are adapted to lhave the endpor.

tions thereof bonded respectively to the slabs, and have their extremeouter ends connected to the bars and the central portions thereofextending through holes in the elastic filler strip and also weakened soas to permit the end portions to move to and fromone another inresponse. to i contraction and expansion of the slabs; and (3) dowelrods which are slidably mounted in the sleeves respectively andconstitute the load transfer members of the joint.

One object of the inventionis to provide'a concrete joint of thistype inwhich the crosssleeves between the load distributing bars have on thecentral portions thereof elements of novel and improved design'forstiffening and reinforcing the elastic fillerl strip 4against sagging orbending during pouring of the concrete in connection withY the formationof the slabs.

-Another object of the invention is to provide a concrete joint of thetype and character under consideration in which the cross-sleeves haveon the center portions rthereof volute springs which are positioned inopposed relation with the stiifening elements and serve yieldingly tohold the ller strip in place against the elements.

A further object of the invention is to lprovide a concrete joint whichis generally of new and improved construction, maybe manufactured at a.low and reasonable cost, `and is an improvement upon previously designedv joints of the same general character by reason of the fact that it iscapable of being assembledat the place of installation with greaterfacility and in less time.

Other objects of the invention and the various advantagescharacteristics of the present concrete joint will be apparent fromv aconsideration or the following detailed description.

The invention consists in the several novel features which arehereinafter set 'forth and are (cl. ysri- 18) j v more particularlydefined `by claims at theconclusion hereof.

In the drawing which accompanies and forms a part of this specificationor disclosure and in which like numerals of reference denotecorresponding parts throughout the several views:

- `Figure 1 is a planview of a joint embodying the invention;

Figure 2 is an enlarged transverse sectional view showing the joint inits operative position 10 `'with respect to a pair of concrete slabs;

. Figure 3 is a fragmentary perspective of the joint showing the mannerin which the legs on the bottom or lower portions of the stiffeningelement for the iiller strip operate in conjunction vwith the volutesprings on the central portions of the cross-sleeve to hold the llerstrip in place against and in firm engagement with the elements; v

Figure 4 is a fragmentary perspective view of 20 one o f the elementsfor stiening the elastic ller strip; v Figure 5 is a detail sectionalview showing one of the volute springs before it is shifted or driv-leny into its-operative position. wherein it serves 25 to hold theadjacent vportion of the elastic ller strip against the contiguous partof the opposite stiffening element; and

Figure 6 is a perspective of one of the caps for connecting theextremities of the cross-sleeves to the .load distributing bars whichare adapted to extend transversely through the slabs.

The joint which is shown in the drawing constitutes the preferredembodiment of the invention and is shown. inv connection with a pair ofconcrete roadway-forming slabs S.v The latter, as shown in Figure 2,vare spaced slightly apart and rest on a bed B. The joint voperates as aload transfer unit and at the same time permits the slabs S of theroadway to expand or contract as the result of changes in temperature orclimatic conditions, It is of unitary design or construction andcomprises as the main or essential parts thereof a iiller strip l, .apair of laterally spaced horizontally extending load distributingbars 8,a plurality of cross-sleeves 9 between the two bars 8, and a set oi'dowel rods I0 in the sleeves.

The ller strip 1 is sponge rubber, or any formed of felt, treated othersuitable elastic or compressible material. It is disposed in a verticalmanner between the opposed faces of the concrete slabs S and serves toprevent dirt, water, and like matter from passing between the slabs.`When the slabs expand as the result of an increase in temperature, thefiller strip I is compressed between the two slabs, and when the slabscontract as the result of a decrease or drop in temperature the strip,due to its elastic na'- ture, expands and thus effectively lls at alltimes the gap, void, or space between the two slabs. The top and bottomsurfaces of the filler strip are respectively substantially fiush orcopla-nar with the top and bottom faces of the slabs.

The load distributing bars 8 are in the form of metallic rods and areassociated with the slabs S respectively. They are disposed in parallelrelation and extend transversely through the slabs, as shown in Figure2. Preferably ther bars are disposed midway between the bottom and i topfaces of the slabs and the ends of the bars terminate adjacent to theside faces of the slabs. The sleeves 9 extend between and at rightangles to the load distributing bars 8 and project throughV holes I I inthe central portion of the elastic filler strip 1. They are disposed ina hori- Zontal position and in parallel relation and are spacedlaterally and equidistantly apart. Any suitable metallic tube stock isused to form the sleeves, and as shown in Figure 2 the sleeves are ofuniform diameter throughout, that is, from end to end. The outer facesof the sleeves are coated with zinc or any other like material whichwhen brought into contact with concrete bonds itself to the concrete asthe result of the chemi-` cal action which takes place. Because of thecoatings the end portions of the sleeves become bonded to the slabs. Inorder to permit the end portions of the sleeves at one side of the llerstrip 'I to move to and from the end portions of the filler strip at theother side of the sleeve the central portions of the sleeves areweakened by way of annular series of slots I2. By employing these slotsthe sleeves are suiciently weakened so that the central portions thereofeither bend or buckle in response to movement of the end portions of thesleeves toward one another or rupture in the event that the end portionsof the sleeves move away from one another as the result of markedcontraction on the part of the slabs S. The slots I2 are disposed midwaybetween the ends of the cross-sleeves and are confined within theportions of the elastic ller strip which define the holes II. The outerextremities of the cross-sleeves 9 have pairs of notches I3 therein.These notches are horizontally aligned and form seats for the loaddistributing bars 8. The inner ends of these notches are curvedconformably to the bars and the outer portions of the notches arenarrower than the bars so that the bars when snapped into, or driveninto seated relation with, the notchesare secured in connected relationwith the sleeves. The outer ends of the sleeves are closed against theingress of concrete during formation of the slabs S by means of caps I4.These caps are in the form of metal stampings and embody circular endwalls I and cylindrical side walls I6. The side walls I8 t over thenotched ends of the cross-sleeves, as shown in Figures 2 and 3, and havehorizontally aligned pairs of notches i 'I which correspond in shape tothe notches I3 in the end portions or extremities of the cross-sleevesand receive the load distributing bars 8. The notches I'I are soarranged that when the caps are in their operative position the endwalls I5, as shown in Figure 2, substantially abut against the end edgesof the cross-sleeves. In assembling the joint prior to pouring of theconcrete in connection with the formation of the slabs S thecrosssleeves 9 are first inserted through the holes II in the centralportion of the elastic filler strip 1 and slid or adjusted relatively tothe strip until the slots l2 are positioned within the holes II.Thereafter the load distributing bars 8 are shifted laterally intoseated relation with the notches I3 in the end portions of thecrosssleeves and the caps I5 are driven into place so as to secure theload distributing bars against lateral displacement with respect to thecrosssleeves and also to close the ends of the sleeves against theingress of concrete. The dowel rods I Il fit snugly and slidably in thesleeves 9 and the ends thereof, as shown in Figure 2, terminate slightlyinwards of the load distributing bars 8. They constitute the loadtransfer members of the joint and are coated with graphite or any othersuitable lubricant prior to insertion in the sleeves so that they arereadily slidable relatively to the latter and thus permit the endportions of the sleeves to move to and from one another in response toexpansion and contraction of the slabs.

In addition to the elastic ller strip 1, the load distributing bars 8,the cross-sleeves 9, and the dowel rods I8, the joint comprises aplurality of elements I8. These elements are in the form of plate metalstampings and serve, as hereinafter described, to stiifen or reinforcethe elastic ller strip 1 so that the latter is held in an upstandingposition and against collapse during pouring of the concrete inconnection with the formation of the slabs S. Preferably there is onestiffening element I8 for two cross-sleeves and the elements, as shownin Figure 1, are arranged in alternate relation, that is, every otherone adjacent to one side of the filler strip and the alternate elementsadjacent to the other side of the strip. The central portions of theelements are deflected longitudinally so that the elements havelongitudinal channels I9 and comprise side walls 28, inwardly extendingtop and bottom walls 2l and 22, and top and bottom fianges 23 and 24.The top and bottom walls serve to space the side walls from the flangesand together with said side walls define the channels I9. The flanges 23and 24 are adapted to abut directly against the elastic filler strip 'Iand operate to prevent transverse bending of the strip. The channels I 9are coextensive with the stiffening elements and are closed at the endsthereof by means of end walls 25. The latter are formed integrally withand extend inwardly from the end margins of the side walls I9 of theelements. The open sides of the channels I9 face the filler strip 'Iwith the result that portions of the filler strips are free to bulge orexpand into the channels when the slabs S expand and place the stripunder compression. The central portions of the side walls Iii of thestiifening elements are deflected inward and then outwardly to formcollars 26 and annular depressions around the collars. The collars, asshown in Figure 3, fit around the central portions of the cross-sleeves9 and serve to hold the stiffening elements against tilting relativelyto the sleeves. 'I'here are two collars for each stiffening elementinasmuch as there is one element for each pair of sleeves. The collarsare the same in length as the channels I9 are in depth and theirinternal diameter is substantially the same as the external diameter ofthe crosssleeves. collars permit concrete to flow around all portions ofthe sleeves with the exception of those parts or portions which aredisposed within the ller The annular depressions around thevprotuberance-like stops 21.

strip. The stiffening' elements are of such length that when thecross-sleeves are spaced equidistantly apart, the ends of the elementslap one another (see Figure 1). Because of this lapping of the endsofthe stiffening elements .the elastic filler strip is stiifened orreinforced throughout the entire lengthv thereof. The reinforcingelements are preferably of such height that the top` and'bottomflanges23 and 24 thereof fit respectively against the upper and lower vportionsof the iiller'strip and hence such portions are held against lateralsagging. The stiifening elements i8 are held against sliding movementaway from the elastic filler strip by means of These stops are formed bystriking or punching outwards the central portions of the cross-sleevesand are adapted to abut against the outer edges of the Icollars`26 ofthe stiffening elements. AThey are so spaced from the true centers ormid-parts of the crosssleeves that the collars when in abutmenttherewith, as shown in Figure` 2, serve centrally to positionthe'i'lller strip on the sleeves.

In order yieldingly to hold the elastic filler strip l in abuttingrelation with the'stiifening elements |8, volute springs 28 areprovided. These springs are mounted on the central 'portions of thecross-sleeves 9 in spaced relation with the stiiiening elements. Theinner convolutions of the springs are slightly smaller in diameter thanthe cross-sleeves with the result that they grip the cross-sleevesfrictionally. In assembling the joint, the sleeves with `the stiffeningelements I8 thereon are inserted through the holes in the filler strip 1and slid transversely of said strip until the latter is brought intoabutting relation with'the stiifening elements. Thereafter the volutesprings 28 are mounted on the sleeves in opposed relation withv thestiffening elements and by way of a hammer or any other suitableimplement are driven toward the stiifening elements until the innerconvolutions thereof substantially abut against the contiguous faceportions of the filler strip 1. When the inner convolutions of the-spring are so positioned the outer convolutions engage yieldingly thestrip and serve to hold the strip in clamped relation with thestiffening elements. By reason of the fact thatthe inner convolutionsofthe springs are smaller in diameter than the cross-sleeves the springsremain in their driven position. The springs are of such outsidediameter or size that a comparatively large part of the central portionof the ller strip is engaged by the springs and hence the strip iseffectively vheld against the stiffening elements. l

In order to support the aforementioned parts of the joint in theirproper positions during pouring of the concrete in the formation of theslabs S the stiffening elements |8 are provided with legs 29. These legsare 'in theform of metal stampings and embody vertically extending parts3B and horizontally extending parts 3|. The vertically extending parts3B are riveted or otherwise fixedly secured to the bottom flanges 24 ofthe stiffening elements and dependfrom such flanges, as shown in Figure2. The horizontally extending parts 3| lof the legs extend under thebottom edge or face of the elastic ller strip l and are designed to restupon the bed B. They are substantially flat and are of ysuch size thatthe legs form a firm support for the joint and prevent the latter fromtilting during the concrete pouring operation. There are' preferably twolegs vfor each stiffening'element. vThe central vinverted portions ofthe horizontally extending parts'3l of the legs are deflectedfupwards`to form inverted V-formation's 32. These formations extendlongitudinalyof the filler vstrip'l.l vThey are disposed beneath thevolute springs 28 and coact with the latter to hold the strips inclamped relation with the stiifening elements. By reason 'of the factthatthe horizontally extending parts 3| of the legs on'every otherstiffening element extend in one direction and the horizontal parts ofthe legs on thel alternate stiiening elements extend in the oppositevdirection the joint is efficiently and rigidly supported. The inverted'V-formations 32 on the parts 3| of the legs are so spaced from thevertically/extending parts oflthe legs that they hook around the lowerportions of the ller strip 'l and hold such portion against lateraldisplacement with respect to said vertically extending parts of thelegs.' .p

It is contemplated that the joint be sent by the manufacturer to theplace of installation in dismantled or knock-down form. In assemblingthe joint the stiffening elements |8'are positioned on the bed B sothatthey are positioned in substantial alignment and also in alternaterelation, that is, one facing in one direction andthe next facing in theopposite direction. Thereafter the elastic ller strip 1 is positioned sothat the bottom edge thereof restsA on the inner portions of thehorizontally extending `parts 3| of the legs 29 and the side facesthereof fit against the top and bottom flanges 23 and 24'of thestiifening elements. When the strip is so positioned the V-formations 32on the horizontally extending parts 3| of the `legs are arranged inhooked relation with respect to the bottom portions of the strip v'l andhold such portions inclamped or fixed relation 'with the verticallyextending parts 3!! ofthe-legs, as hereinbefore described. Afterpositioning the filler strip in the aforementioned mannerthe'cross-sleeves 9 are inserted through the collars26 of the stiffeningelements and the holes in the filler strip and slid longitudinally so asto bring the slots I2 within the hole defining portions of the fillerstrip and the protuberance-like strips 2'! into abutting relation withthe outer edges of the collars 26 of the stiening elements. Aftershifting the cross-sleeves in this manner the volute springs 28 aremounted on the sleeves 9 and driven inwardly until they are disposed inopposed relation with the stirfening elements and engage' yieldingly thefiller strip'and hold the latter in clamped relation with said elements.As hereinbeforepointed out, the springs are preferably driven or slid onthe sleeves until the inner convolutions thereof substantially abutagainst the filler strip in order to place the outer convolutions underspring pressure as far as the strip is concerned. After driving of thevolute springs into place the loadl distributing bars 8 are connected tothe endportions or extremities of the cross-sleeve by shifting them intoseated relation with the notches I3 and then applying the caps I4 to theextremities of the sleeves.y The joint, after assembly thereof, isproperly positioned on the lbed B and thereafter the concrete is pouredon opposite sides thereof to form the slabs S. During pouring of theconcrete the legs 29 hold the joint against tilting, as hereinbeforepointed out. The herein described `ioint may be manufactured at acomparatively low cost because it consists of but a small number ofAparts. It may be assembled with facility andspeed and is characterizedby the fact that the elastic filler strip is so stiffened or reinforcedthat it cannot sag or buckleduring pouring of the concrete.

Vihereas the joint has been described as comprising load distributingbars and also crosssleeves with dowel rods therein, it is to beunderstood that the joint may be used'without the load distributing barsand also that solid or onepiece cross-members may be substituted for thecross-sleeves and dowel rods. It is also to be understood that theinvention is not to be restricted to the details set forth, since thesemay be modified within the scope of the appended claims, withoutdeparting from the spirit and scope of the invention.

Having Athus described the invention what we claim as new and desire tosecure by Letters Patent is:

A joint for contiguous concrete slabs, comprising in combination acompressible ller strip adapted to fit between the slabs and yield inresponse to expansion thereof, a plurality of laterally spacedcross-members adapted to have the end portions thereof embedded in theslabs respectively and having their central portions extending throughholes in the strip, and strip engaging elements` for stiffening thestrip and holding it against lateral displacement during pouring of theconcrete in connection with formation of the slabs, mounted and held onsaid central portions of the cross-members against movement away fromthe strip and arranged so that every other one engages one side face ofthe strip and the alternate ones engage the other side face of' thestrip and also so that the ends thereof are disposed in lapped relation.

2. A joint for contiguous concrete slabs, comprising in combination anelongated compressible filler strip adapted to fit between the slabs andto yield in response to expansion thereof, a plurality of laterallyspaced cross-members adapted to have the end portions thereof embeddedin the slabs respectively and having their central portions extendingthrough the central portion of the strip, an elongated strip stiffeningelement fitting against one side of the strip and mounted on the centralportions of certain of the crossmembers against movement away from thestrip, and a second elongated strip stiffening element mounted on thecentral portions of certain other cross-members so that it engages theother side face of the strip and is held against movement away from saidstrip, and arranged so that one end thereof is disposed in lappedrelation with one end of the first mentioned stiffening element.

3. A joint for contiguous concrete slabs, comprising in combination acompressible filler strip adapted to t between the slabs and yield inrespense to expansion thereof, a pair of laterally spaced cross-membersadapted to have the end portions thereof embedded in the slabsrespectively and having their central portions extending through thestrip, an elongated stamped metal stiiening element for stiffening thestrip and holding it in place during pouring of the concrete for theslabs and fitting against one of the side faces of the strip and havingthe central portion thereof deflected longitudinally from end to end toform a channel with an open inner side, for receiving'and accommodatingthe contiguous portions of the strip when said strip is compressed asthe result of slab expansion, and also having endv parts for closing theends of the channel and additional parts forming integral collars whichare disposed within the channel and have annular outwardly openinggrooves therearound and forming bearings for the central portions ofsaid cross-members.

4. A joint for contiguous concrete slabs, comprising in combination acompressible ller strip adapted to fit between the slabs and yield inresponse to expansion thereof, a plurality of laterally spacedcross-members adapted to have the end portions thereof embedded in theslabs respectively and having their central portions extending throughholes in the strip, stiffening elements for the strip mounted on thecentral portions of the cross-members held against movement away fromthe strip, and resilient means mounted on said central portions of thecrossmembers in opposed relation with the elements for holding the stripin clamped relation with said elements.

5. A joint for contiguous concrete slabs, comprising in combination acompressible ller strip adapted to t between the slabs and yield inresponse to expansion thereof, a plurality of laterally spacedcross-members adapted to have the endportions thereof embedded intheslabs respectively and having their central portions extending throughholes in the strip, stiening elements for the strip mounted on thecentral portions of the cross-members and held against movement awayfrom the strip, and springs mounted on said central portions or" thecrossrnembers in opposed relation with the stiffening elements andarranged yieldingly to hold the strip in clamped relation with saidelements.

6. A joint for contiguous concrete slabs, comprising in combination acompressible filler strip adapted to fit between the slabs and yield inresponse to expansion thereof, a plurality of laterally spacedcross-members adapted to have the end portions thereof embedded in theslabs respectively and having their central portions extending throughholes in the strip, stiffening elements for the strip mounted on thecentral portions of the cross-members, and springs of the spiral varietyextending around and frictionally gripping said central portions of thecross-members and arranged in opposed relation with the stiffeningelements and so that they operate yieldingly to hold the strip inclamped relation with said elements.

'7. A joint for contiguous concrete slabs, comprising in combination afiller strip adapted to nt between the slabs, a plurality of laterallyspaced cross-members adapted to have the end portions thereof embeddedin the slabs respectively and having their central portions extendingthrough holes in the strip, elements on the central portions of themembers for holding the filler strip against sidewise displacement inone direction relatively to the members, and springs mounted on saidcentral portions of the members in opposed relation to said elements andserving yieldingly to opposed lateral displacement of the strip in theopposite direction.

8. A joint for contiguous concrete slabs, comprising in combination afiller strip adapted to fit between the slabs, a plurality of laterallyspaced cross-members adapted to have the end portions thereof embeddedin the slabs respectively and having their central portions extendingthrough holes in the strip, elements on the central portions of themembers for holding the filler strip against sidewise displacement inone direction relatively to the member, and volute springs mounted onsaid central portions of the members in opposed relation with theelements and arranged so that they engage the strip yieldingly andoppose lateral displacement in the opposite direction.

9. A joint for contiguous concrete slabs, comprising in combination aller strip adapted tov fit between'the slabs, a plurality of laterallyspaced cross-members adapted to have the end portions thereof embeddedin the slabs respectively and having their central portions extendingthrough holes in the strip, and means for stiiening the strip andholding .it against lateral displacement With respect to said crossmembers including springs of the spiral variety mounted on said centralportions of the members and engaging yieldingly said strip.

10. A joint for contiguous concrete slabs, comprising in combination afiller strip adapted to t between the slabs, a plurality of laterallyspaced cross-members adapted to have the end portions thereof embeddedin the slabs respectively and having their central portions extendingthrough holes in the strip, and means `for stifening the strip andholding it against lateral displacement with respect to saidcross-members including volute springs mounted on andgrippingfrictionally said central portions of the members and arranged so thatthey engage yieldingly said strip.

ERNEST H. GEYER. HENRY A. TAUBENSEE.

